System and method for improving performance of a data backup operation

Abstract

This invention is a system and method for improving performance of a backup operation of data from a data storage system to a media library. In response to a computer system request to backup a slot or track of data, a data engine in communication with the system and a data storage system selectively reads the requested data. Such data engine reads may occur concurrent to host access for I/O operations by employing a protection scheme, e.g. a protection bit. Simultaneously, different backup sessions may read the same track of data that has been read by the data engine. The data slot or track remains in cache memory of the data storage system until all protection bits are reset. A requested slot or track may be moved to a sidefile stored in the cache memory if a host requested to write to it while protection bits are still set and then sent to the Data engine for transfer to a media library.

What is claimed is:  
     
       1. In a data storage environment having a data storage system with memory and at least one data storage device and wherein the data storage system is in communication with a host computer and a data engine also having memory, and wherein the data engine is in communication with a media library unit, a method for managing data that is involved in a backup operation, the method comprising the steps of: 
       responsive to a first backup session request from the host to backup a track of data, the data engine selectively reading the requested track of data into cache memory associated with the data engine;  
       assigning a protected status for the read track of data in cache memory; and  
       allowing simultaneous access to the read track of data for one or more host backup sessions that may occur subsequent to the first backup session until the protected status is changed to an unprotected status.  
     
     
       2. The method of  claim 1 , wherein the read track of data assigned a protected status is accessible for an host I/O operation until the protected status is changed to an unprotected status. 
     
     
       3. The method of  claim 2 , wherein the host I/O operation is a write operation. 
     
     
       4. The method of  claim 3 , wherein a write pending condition is assigned to indicate the write operation for the read track of data that has a protected status. 
     
     
       5. The method of  claim 4 , wherein the read track of data is copied to a sidefile stored in memory in response to the write pending condition being assigned. 
     
     
       6. The method of  claim 5 , wherein the write operation operates on the copy of the read track of data stored in the sidefile in memory. 
     
     
       7. The method of  claim 6 , wherein the data operated on by the write operation is sent to the data engine for transfer to the media library unit. 
     
     
       8. In a data storage environment having a data storage system with memory and at least one data storage device and wherein the data storage system is in communication with a host computer and a data engine, and the data engine is in communication with a media library unit, a method for managing data that is involved in a backup operation, the method comprising the steps of: 
       responsive to a first backup session request from the host to backup a track of data, the data engine selectively reading the requested track of data into cache memory associated with the data engine;  
       assigning a protected status for the read track of data in cache memory; and  
       allowing simultaneous access to the read track of data for one or more host backup sessions that may occur subsequent to the first backup session until the protected status is changed to an unprotected status.  
     
     
       9. The method of  claim 8 , wherein the host I/O operation is a write operation. 
     
     
       10. The method of  claim 9 , wherein a write pending condition is assigned to indicate the write operation for the read track of data that has a protected status. 
     
     
       11. The method of  claim 10 , wherein the read track of data is copied to a sidefile stored in memory in response to the write pending condition being assigned. 
     
     
       12. The method of  claim 11 , wherein the write operation operates on the copy of the read track of data stored in the sidefile in memory. 
     
     
       13. The method of  claim 12 , wherein the data operated on by the write operation is sent to the data engine for transfer to the media library unit. 
     
     
       14. A computer system comprising: 
       a data storage system including memory and at least one storage device;  
       a host computer system in communication with the data storage system;  
       a data engine having memory in communication with the data storage system;  
       a media library in communication with the data engine; and  
       computer-executable logic in communication with the data storage system and the data engine that enables the method steps of:  
       responsive to a first backup session request from the host to backup a track of data, the data engine selectively reading the requested track of data into cache memory associated with the data engine;  
       assigning a protected status for the read track of data in cache memory; and  
       allowing simultaneous access to the read track of data for one or more host backup sessions that may occur subsequent to the first backup session until the protected status is changed to an unprotected status.  
     
     
       15. The system of  claim 14 , wherein the read track of data assigned a protected status is accessible for an host I/O operation until the protected status is changed to an unprotected status. 
     
     
       16. The system of  claim 14 , wherein the host I/O operation is a write operation. 
     
     
       17. The system of  claim 16 , wherein a write pending condition is assigned to indicate the write operation for the read track of data that has a protected status. 
     
     
       18. The system of  claim 17 , wherein the read track of data is copied to a sidefile stored in memory in response to the write pending condition being assigned. 
     
     
       19. The system of  claim 18 , wherein the write operation operates on the copy of the read track of data stored in the sidefile in memory. 
     
     
       20. The system of  claim 19 , wherein the data operated on by the write operation is sent to the data engine for transfer to the media library unit. 
     
     
       21. A program product for use with a data storage system having memory and at least one storage device and which is in communication with a computer system, a data engine, and a media library unit, the program product being for carrying out a restore operation and being comprised of: 
       computer-executable logic configured for causing the following computer-executed steps to occur:  
       responsive to a first backup session request from the host to backup a track of data, the data engine selectively reading the requested track of data into cache memory associated with the data engine;  
       assigning a protected status for the read track of data in cache memory; and allowing simultaneous access to the read track of data for one or more host backup sessions that may occur subsequent to the first backup session until the protected status is changed to an unprotected status.  
     
     
       22. An apparatus for managing data involved in a backup operation, the apparatus comprising: 
       a data storage system with memory and at least one data storage device;  
       a host computer in communication with the data storage system;  
       a data engine also having memory and being in communication with the data storage system;  
       a media library unit in communication with the data engine and wherein the apparatus includes:  
       means responsive to a first backup session request from the host to backup a track of data, the data engine selectively reading the requested track of data into cache memory associated with the data engine;  
       means for assigning a protected status for the read track of data in cache memory; and  
       means for allowing simultaneous access to the read track of data for one or more host backup sessions that may occur subsequent to the first backup session until the protected status is changed to an unprotected status.